Radio receiving system



Deco M, 1923., 3,4714% E. F. w. ALEXANDERSON RADIO RECEIVING SYSTEM Filed June 24, 1921 \l AAAAAAA l 4 Inventor: Ennst F. \A/ Alexanderson,

byflw His Attorney lFatemtcd Deco ill, i923,

narrate stares rarest orrroa.

= ERSON, OF SCHENECTADY, NEW YORK, ASSIG-NOB T0 GENERAL ECTRIC COMJPANY, A CORPORATION OF NEW YORK.

Application filed June at,

systems with the'reception of desired sigrials.

The object of'my invention is to provide iii a radio receiving system a means for pre- 1921. Serial No. $802920.

tuned resistance of the first circuit is substa'ntially equal to the series tuned resistance of the second circuit. Each of the circuits has the character of a non-inductive resistance at the frequency to which they are tuned, hence the voltage drops between the terminals of each of these two circuits are equal and in phase. The voltage drop upon the receiving circuit which is associated with a detector 9 of the audion type.

venting interference with the reception of The couplings 7 and 8.are so arranged that desired signals froma near-by transmitting stationhaving a difierent wave length.

In carrying my invention into effect I provide 1n connection with a receiving an v tenna means for impressing upon the receivmultiple tuned circuit made up of ing circuit two equal and opposin potenv tials producedin the antenna by't e inter-V fering wave. This means is so arranged that it will also impress upon the receiving circuit two potentials produced bythe desired signaling waves, but these two potentials will be of difi'erent magnitude and of the same phase or will have such phase relation to each other that they will add in the receiving circuit and will not neutralize one another. I

The novel features which I believe to be characteristic of my invention are set forth in the appended claims. The invention itself, however, both as to its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawing in which I have indicated diagrammatically one Way in which my invention may be carried into effect.

As indicated in the drawing, I provide in connection with the receiving antenna 1 in addition to the ordinary antenna tuning coil 2, two special tuned circuits, one being a inductance 3 andcapacity 4 and the other being a series tuned circuit made up of inducta ace 5 and capacity 6; These two circuits are adjusted so that they are both in resonance for the, signal which it is desired to suppress. The inductances and capacities of these two circuits are selected so that the multiple by Letters Patent the potentials of a frequency equal to that of the waves to be suppressed oppose eaclr other in the receiving circuit and their eilect is thus neutralized. Thus no signal will be received or detected of the .-frequency for which the two circuits are tuned. If, how ever, the frequency of the signal to be received is only sli htl greater than the frequency .for whic tuned the multiple tuned circuit assumes the character of a capacit and the series tuned circuit assumes the character of an induct ese two circuits are tance; Thus the phase of the voltage drops produced by the desired signal across the two circuits is shifted in opposite directions. By properly proportioning the circuits the voltage drops by the desire signal may. be made to be substantially opposite in phase so that they will add in the receiving circuit. The magnitude of the voltage drop across the multiple tunedcircuit will also be less than the voltagedrop across the series tuned circuit. It will thus be apparent that the si al which has a frequency onl slightly di erent from that of the inter ering wave may be received with practically full intensity at roduced acrossthese circuits I the same time that the interfering wave 1s neutralized. 7

What I claim as new and desire to secure of the United States, is

1. Means for eliminating disturbing effe'cts in a radio receiving system comprising a receiving antenna, a multiple tuned cir cuit connected to said antenna which isresonant to the frequency of the disturbing efiect to be eliminated, a series tuned'circuitconnected to said antenna which is also resonant to the frequency of the disturbing efi'ect to be eliminated, a receiving circuit and means for impressing upon the receiving circuit electromotive forces derived from both of said resonant circuits.

2. Means for eliminating disturbing effects in a radio receiving system comprising a receiving antenna, a multiple tuned circuit connected to said antenna which is resonant to the frequency of the disturbing effect to be eliminated, a series tuned circuit connected to said antenna which is also resonant to the frequency of the disturbing effect to be eliminated, the multiple tuned resistance of the first circuit being substantially equal to the series tuned resistance of the second, a receiving circuit and means for impressing upon the receiving circuit eiec- I tromotive forces derived from both of said resonant circuits. v

3. A receiving system for radio signals comprising a receiving antenna and means for deriving from said antenna and impressing upon a receiving circuit two radio frequency electromotive forces of equal intensity and opposite-sign produced by undesired waves of definite frequency in said antenna, said meansbeing arranged to im-- press upon the receiving circuit two electromotive forces produced in said antenna by desired signaling currents and which will add in the receiving circuit.

In witness whereof, I have hereunto set my hand this 23rd day of June, 1921 ERNST F. W. ALEXANDERSON. 

